Properties of Red Mud-Lime Solidified Cadmium and Lead Contaminated Soil under Acidic Dry-Wet Cycle
To achieve the goal of utilizing solid waste resources and turning waste into treasure,red mud-lime was proposed as a solidifying agent for the solidification/stabilization treatment of cadmium and lead heavy metal contaminated soil.The effects of different ratios of solidifying agents,pollutant concentrations,solution pH values,and dry-wet cycle times on mass loss rate,strength change,toxicity leaching concentration and microstructural morphology were studied through acid dry-wet cycle tests,unconfined compressive strength tests,toxicity leaching tests,and microscopic structure analysis.Results showed that R4C4 solidified soil had the lowest mass loss rate under various conditions.Under the dry-wet cycle with solution pH=7,the compressive strength of the solidified soil increased with the increase of lime content.As the cycle times increased,the strength increased first and then decreased,reaching a peak at two cycles.As the pH value of the solution decreased,the strength also decreased.The leaching concentration increased with the increase of the cycle times and the pH value of the solution.All samples met the standard requirements at initial concentration M1.After multiple wet-dry cycles,cracks appeared in the soil and reduced hydration products led to structural damage.
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